This invention relates to improvements in exterior stucco-look finishing systems such as, for example, exterior insulation and finish systems (EIFS) and direct-applied exterior finish systems (DEFS) for buildings. Such EIFS systems are fully described in U.S. Pat. No. 4,647,496. More particularly, this invention relates to an improvement in the management of water as a line of defense by harmlessly handling any unwanted water that has penetrated behind the exterior cladding.
Originally, EIFS was an exterior wall concept designed to have high insulation values and a reliable stucco finish that could be economically created in a wide array of textures and colors. It immediately became successful because it provided so much performance for so little cost. The most unusual aspect of the system was that expanded polystyrene (EPS) insulation was installed on the exterior side of the wall by adhesively binding it to a substrate, forming a base for an exterior coating as well as adding more insulation to the building. The surface typically has a xe2x85x9-inch-thick synthetic-stucco finish system which performs two functions. It is designed to (1) provide a face-seal or barrier to seal out moisture and (2) provide a decorative finish at the same time. This xe2x85x9-inch-thick finish system consists of reinforcing mesh, latex-fortified basecoat, and an aggregated, polymeric, textured finish.
The principal weaknesses in the prior art EIFS is that they have only one line of defense against water intrusion and no means to drain intruding water. Although the surface usually forms an effective water barrier, intersections of the surface with other elements, such as window frames, door frames, etc., often leave gaps or openings that driving rain can penetrate. Once inside the sealed wall and behind the cladding, the water can remain trapped long enough before evaporating to damage or rot any water-sensitive elements, to which the insulation is bonded including, oriented-strand board, plywood, or gypsum sheathing.
Whether the prior art exterior wall systems provide an insulation layer attached to the exterior sheathing which is coated with a stucco-look finish (EIFS), or the stucco-look finish is applied directly over the sheathing (DEFS), there has been no provision for water managed relief at the back side of the sheathing.
As a result of these problems, a need has arisen for water-managed stucco-look systems. The present invention discloses exterior wall systems that provide the designer and building owner with the popular esthetics of synthetic stucco and the long-term reliability of water management.
Prior art building systems have sought to effectively achieve water management. In fact, many common exterior claddings can be considered water managed. Brick veneer, for instance, is typically detailed with a cavity between the face brick and a protected wall framing. This cavity creates a drainage plane, and with weeps at the foundation, it allows water that has penetrated the brick to be removed to the outside.
The disclosed water managed exterior system efficiently directs the penetrating water to weeps or the like. Should water flank the synthetic stucco cladding, or enter openings for penetrations, it will be stopped at the weather-resistive barrier, then drained to flashing elements, and removed to the outside through the weeps, thereby protecting the stud cavity and any water sensitive materials in the wall cavity from damage.
In a preferred embodiment, the system utilizes a water durable board, such as the DUROCK(copyright) Cement Board, as a substrate for insulation, basecoat and finish materials. The interior side of the water durable board is textured to form a water managed plane that allows any water that penetrates to collect along the textures and drain down the interstitial spaces created by the textures. In a more preferred embodiment, the textured plane is a dimple pattern or grooves on the interior surface of the water durable board. The dimple pattern or grooves create a myriad of vertical sinuous flow paths for the water to drain downwards.
The system can be installed over wood- or steel-stud framing; a structural sheathing may be used, depending on the design criteria. Flashing components are installed, along with a weather-resistive barrier, such as a standard No. 15 felt. Wrapping this barrier into openings protects window and door penetrations. Following the application of the water durable board, foam insulation is bonded to the board and then a layer of reinforced basecoat is applied to the entire surface and allowed to dry. In DEFS applications no insulation is applied and the basecoat is applied directly to the durable board surface. To complete the wall, a pre-colored finish such as USG EXTERIOR Textured Finish, is trowel-applied and floated to the desired look.